One example of a device is disclosed in “http://www.nintendo.co.jp/wii/controllers/index.html”. Nintendo's “Wii remote controller” (Wii: registered trademark) has a three-axis motion sensor for detecting tilt and _motion of the controller. NunchukThe Nunchuk controller also has a three-axis motion sensor. The Wii remote controller as a main controller is provided with an expansion connector, and theNunchukNunchuk as an expansion controller is connected to the Wii remote controller via the expansion connector.
In certain games, the player performs an operation by holding the Wii remote controller with one hand and by moving the Wii remote controller. In other games, while holding the Wii remote controller with one hand, and the Nunchuk with the other hand, the player performs an operation by moving each of the Wii remote controller and the Nunchuk.
However, since the Wii remote controller and the Nunchuk are only provided with acceleration sensors as motion sensors, it is not easy to detect a rotative motion especially on a principle plane. More specifically, if a slice shot is made in a tennis game, for example, an angular velocity or a rotation angle about the Wii remote controller have to be detected with high accuracy. These variables can be calculated from the accelerations in the three-axis directions detected by the acceleration sensor, but acceleration in each of the three-axis directions also includes an acceleration component by gravity, so that complex calculation would be required for evaluating the angular velocity or rotation angle with high accuracy.
This requires that a routine for such calculation has to be incorporated in an individual game program, which imposes extra work on game developers. Furthermore, by repetitively executing such calculations, a high load is imposed on a CPU of a game apparatus.
It is conceivable that a gyro sensor for detecting an angular velocity could be connected to the Wii remote controller via the expansion connector. However, even if such a gyro sensor is so connected, the Nunchuk cannot be used. It would become impossible to play a game utilizing both of the Wii remote controller and the Nunchuk.
Furthermore, the Wii remote controller can be attached with a strap, and the wrist of the hand holding the Wii remote controller runs through the ring of the strap attached to the Wii remote controller. The connector of the Nunchuk is provided with a hook, and the cord of the strap attached to the Wii remote controller is hung and retained with the hook of the connector of the Nunchuk. Thus, the connector of the Nunchuk and the expansion connector of the Wii remote controller are firmly secured to each other.
On the other hand, as described above, in a case that a gyro sensor for detecting an angular velocity is connected to the Wii remote controller via the expansion connector, it is desirable that the gyro sensor is provided with another expansion connector in order that a game can be played even in a state that the gyro sensor is connected to the expansion connector of the Wii remote controller.
However, in a case that the connector of the Nunchuk is connected to the expansion connector on a side of the gyro sensor, that is, in a case that there is a gyro sensor between the Wii remote controller and the connector of the Nunchuk, it is difficult to retain the cord of the strap with the hook of the connector of the Nunchuk.